1. Field of the Invention
This invention relates to alkyl and/or alkenyl oligoglycoside carbonates, to a process for their production and to their use for the production of surfactants.
2. Statement of Related Art
For some years now, there has been an increasing trend to produce speciality chemicals for detergents from renewable raw materials, such as for example sugar or starch. One example of this are the alkyl oligoglycosides which, for example, may form an alternative to conventional nonionic surfactants based on fatty alcohol and ethylene oxide. However, the properties of alkyl oligoglycosides are not entirely satisfactory for certain cosmetic applications. Accordingly, esters of alkyl oligoglycosides with carboxylic acids of varying chain length are preferably used instead of alkyl oligoglycosides (Seifen- Ole-Fette-Wachse, 117, 124 (1991).
However, the production of these alkyl oligoglycoside esters is attended by two problems, namely:
1. the thermal instability of the glycoside base under the esterification conditions with the danger of caramelization and
2. the inadequate solubility of alkyl oligoglycosides in standard solvents.
There has been no shortage of attempts in the past to provide technical solutions to these problems:
For example, Gibbons and Swanson report in J. Am. Oil Chem. Soc., 36, 553 (1959) on their efforts to prepare mono- and diesters from methyl glucoside and fatty acids in the presence of sodium hydroxide, lead oxide and tin soap in xylene as solvent. However, any process for the production of cosmetic products which involves the use of xylene and lead compounds is extremely critical in toxicological terms.
The attempts made by Albano-Garcia and Lorica to repeat the esterification in the presence of acidic and basic catalysts in DMF proved unsatisfactory. The reaction products were inhomogeneous and caramelized. The esterification of coconut oil with methyl glucosides using metallic sodium and potassium soap as catalysts also produced dark-colored products which had to be purified with ethyl acetate and water (J. Coconut. Stud., 5(1), 51 (1980)). A process as complicated as this is also totally unsuitable for working on an industrial scale.
Finally, Zedlinski reports on the direct esterification of fatty acid chlorides with methyl glucoside in Bull. Acad. Polon, Sci. 9, 103 (1961). However, the use of fatty acid chlorides imposes stringent works safety requirements and is undesirable for this reason alone.
Accordingly, the problem addressed by the present invention was to provide new alkyl and/or alkenyl oligoglucoside esters of which the production would not be attended by the disadvantages described above.